The Analysis on Distribution Features and Sedimentary Facies variation through Middle Ordovician to Lower Silurian Sequences in the Northwestern Margin of Tarim Basin from Remote Sensing Data

Key words: 
• Northwestern margin of Tarim Basin /
• Middle Ordovician series /
• Lower Silurian series /
• Image lithostratigraphic unit /
• TM ratio technique /
• Evolution of sedimentary facies

Abstract: The Paleozoic sequences are well developed in Kalpin Uplift. The lithostratigraphic sequences from Middle Ordovician to Lower Silurian have been effectively distinguished and correlated by using Landsat TM ratio composite imagery (3/1 (Y) 2/3 (M) 7/5 (C)). Lateral faices variation and spatial distribution of lithostratigraphic sequences can be also traced and delimited.The analysis of TM ratio composite imagery shows that the depocenter of Middle Ordovician series gradually migrated toward the southeast, and the lower part of Lower Silurian is red bed of marine factes in the western part, it becomes to green bed of marine factes in the eastern part. The results indicate that the differential elevation and subsidence movement occurred during the end of Early Ordovician to Early Silurian from the west to the east, and the relevant paleotopography is from high to low in the studied area.Yingan Formation has been first found that it not only distributes in the Yingan Mountain, but also distribute in the middle part of the Yimugantawu Mountain and the eastern part of the Kalpintage Mountain by the analysis of TM ratio composite imagery. We can infer that Shaergan and Yingan Formations, which are favourable source rocks in Tarim Basin, distribute widespreadly in the North Tarim Depression and North Tarim Uplift.The results of this study provide new data and evidence for the research of the Lower Paleozoic source rocks and petroleum exploration of Tarim Basin, and show that the remote sensing technology is a useful way for petroleum exploration in Northwestern China.